On Mon, Jul 13, 2020 at 12:57 PM David G. Johnston <david.g.johns...@gmail.com> wrote: > To be clear, by "escape hatch" you mean "add a GUC that instructs the > PostgreSQL executor to ignore hash_mem when deciding whether to spill the > contents of the hash table to disk - IOW to never spill the contents of a > hash table to disk"?
Yes, that's what that means. > If so that seems separate from whether to add a hash_mem GUC to provide finer > grained control - people may well want both. They might want the escape hatch too, as an additional measure, but my assumption is that anybody in favor of the hash_mem/hash_mem_multiplier proposal takes that position because they think that it's the principled solution. That's the kind of subtlety that is bound to get lost when summarizing general sentiment at a high level. In any case no individual has seriously argued that there is a simultaneous need for both -- at least not yet. This thread is already enormous, and very hard to keep up with. I'm trying to draw a line under the discussion. For my part, I have compromised on the important question of the default value of hash_mem_multiplier -- I am writing a new version of the patch that makes the default 1.0 (i.e. no behavioral changes by default). > I would prefer DavidJ as an abbreviation - my middle initial can be dropped > when referring to me. Sorry about that. -- Peter Geoghegan
